Aqueous Manganese Dioxide Ink for High Performance Capacitive Energy Storage Devices

We report a simple approach to fabricate high performance energy storage devices based on aqueous inorganic ink comprised of hexagonal MnO 2 nanosheets. The MnO 2 ink exhibits long term stability. Continuous thin films can be formed on various substrates without using any binder. To obtain a flexible electrode for capacitive energy storage, we printed the MnO 2 ink on commercially available A4 paper pre-treated by multi-walled carbon nanotubes. The electrode exhibited a maximum specific capacitance of 90.8 mF/cm 2 . The electrode could maintain 98.7% capacitance retention for 1,000 cycles at 10 mV/s. The MnO 2 ink could be a potential candidate for large-scale production of flexible and printable electronic devices for energy storage and conversion.